The present invention relates to a packaging system for preserving perishable items which involves a thermoplastic reclosable bag or container wherein the thermoplastic reclosable bag or container involves sealed means for closing one end of the thermoplastic reclosable bag or container, and an external patch for delivering active packaging materials (e.g., chemicals) into the thermoplastic reclosable bag or container, and means for flowing active packaging materials into the thermoplastic reclosable bag or container from the external patch into the thermoplastic reclosable bag or container.
Plastic containers play an important role in the packaging and storage of foods, medicines, and other goods. Plastics in packaging can perform a variety of tasks including physical protection of the contents and control of the package atmosphere and moisture. Modified Atmosphere Packaging (MAP), made possible by the gas exchange properties of plastics, is used to package fruits, vegetables, baked goods, fresh and processed meats, and cooked poultry. Through this process, fresh produce and other food products can be packaged in controlled atmospheres that maintain the carbon dioxide/oxygen ratio at an optimum level, thus greatly extending the shelf life of these commodities.
“Active Packaging” is being developed that responds to environmental conditions in packages and modifies these conditions to extend the freshness of commodities placed in them. Controlling the gaseous environment in plastic packages is an important aspect of active packaging. In order to do this, a variety of gas scrubbers and emitters have been developed. For example, ethylene is a gaseous natural plant hormone that accelerates ripening in a number of fruits and vegetables. Build-up of ethylene inside a package during storage or transportation can cause premature ripening and accelerated senescence, leading to significant deterioration of organoleptic and physical properties of produce prior to reaching its destination. Ethylene scavenging technologies are being developed to reduce this undesirable build up of ethylene in plastic packages.
Active packaging technologies also exist to control the concentrations of oxygen and carbon dioxide inside the package. These take the form of oxygen scavengers and carbon dioxide emitters/scrubbers. Oxygen scavenging technologies are generally based on one of the following concepts: iron powder oxidation, ascorbic acid oxidation, photosensitive dye oxidation, and enzymatic oxidation. The majority of presently available oxygen scavengers are based on the principle of iron oxidation. Sachets containing chemicals that react to scavenge oxygen are placed in plastic packages to reduce their oxygen content. Some important iron-based O2 absorbent sachets are Ageless® (Mitsubishi Gas Chemical Co., Japan); ATCO®; O2 scavenger (Standa Industrie, France); Freshilizer® (Toppan Printing Co., Japan); Vitalon (Toagosei Chem. Industry Co., Japan); Seagul (Nippon Soda Co., Japan); Fresh Pax® (Multisorb Technologies, Inc., U.S.A.); and O-Buster® (Dessicare, LTD., U.S.A.). Oxygen scavenging plastics have been developed to reduce the oxygen level in plastic containers. The oxygen scavenging chemicals can be incorporated into packaging material such as polymer film, labels, and liners.
Sachets and films are also used as delivery systems for antimicrobial compounds that are introduced into the headspace of active packaging. Examples include chlorine dioxide, silver salts, bacteriocins, ozone, and natural essential oils such as hinokitiol and rosemary. Commercial ethanol emitters also exist (e.g., Ethicap, Antimold 102 and Negamold (Freund Industrial); Oitech (Nippon Kayaku); ET Pack (Ueno Seigaku); and Ageless type SE (Mitsubishi Gas Chemical) (Day 1998). These films and sachets contain absorbed ethanol in a carrier material that allows the controlled release of ethanol vapors.
All of the above active package technologies are applied either in sachets that are placed in the package or incorporated into the plastic (e.g., through a film) that comprises the plastic package. These two means of applying active packaging technologies have considerable problems. The introduction of sachets into packages may allow for the possible accidental ingestion of the contents of the sachet by the consumer. Another concern is that the contents of the sachet will leak out and contaminate the product. Also, when sachets are used there needs to be a free flow of air surrounding the sachet for maximum efficiency. A major problem with O2 and ethylene scavenging packaging film is that the film reacts with the atmosphere prior to its use thereby reducing its intended effectiveness.
The present invention solves problems that presently exist in sachet and film delivery systems for active packaging. It discloses a patch for plastic packages that sequesters active packaging compounds on the outside of the package while allowing free gas and moisture exchange between the contents of the package and the patch. This configuration overcomes the disadvantages stated above for active packaging utilizing sachets and films. The reactive chemicals used for scavenging and emitting active compounds can exist in a dry un-reactive form in the external patch until moisture from the package contents activates them. Having the contents of the patch sequestered outside the package prevents it accidental ingestion or spillage into the package.